Currently, liquid crystal displays (LCDs), due to their advantages such as low radiation, small volume, low power consumption and the like, have gradually replaced conventional cathode ray tube (CRT) displays, and are widely applied in notebook computers, portable android device (Pad), flat-screen TVs, etc. Liquid crystal (LC) molecules have double refractive indices (ne, no), and have different polarization and refraction effects on light under different arrangement states, thus functioning as light valves. The function of liquid crystals as light valves can be used to adjust light field intensity of a backlight, so as to achieve gray scale display, and further achieve color display in conjunction with color filtering function of a light filter. Depending on driving manner, the liquid crystal displays can mainly be divided into a passive-matrix type and an active-matrix type.
At present, mainstream products in the market are all driven in an active-matrix manner. As shown in FIG. 1, an existing liquid crystal display panel includes a first substrate (color filter substrate) 1 and a second substrate (array substrate) 2 arranged opposite to each other, and a liquid crystal layer 3 formed between the first substrate 1 and the second substrate 2. Flat panel pixel design, in which the first substrate 1 and the second substrate 2 keep parallel in a horizontal direction, is generally adopted in the existing liquid crystal display panel. When a viewer looks at the display screen from a front viewing angle (0° direction in FIG. 1), a cell thickness d of each sub-pixel is substantially the same, i.e., d=d0, an optical path difference of each sub-pixel is also the same, i.e., Δn*d=Δn*d0 (wherein Δn=ne−no), and thus ratios of liquid crystal light efficiency to transmittance for red/green/blue (R/G/B) sub-pixels are the same. When viewed from an oblique angle θ (i.e., viewing angle), the liquid crystal molecule has an optical path difference of Δn*d0/cos θ=Δn*dθ, that is, an increased optical path difference, so liquid crystal light efficiency and transmittance for red/green/blue (R/G/B) light vary differently, and thus brightness ratio is no longer constant. That is to say in the case of a large viewing angle, transmittance varies among pixels of different colors. In FIG. 2, CF0 (λ) is a transmittance spectrum of the liquid crystal panel at the front viewing angle of 0° viewing angle, CF30 (λ) is a transmittance spectrum of the liquid crystal panel at the oblique viewing angle of 30° viewing angle, and CF60 (λ) is a transmittance spectrum of the liquid crystal panel at the oblique viewing angle of 60° viewing angle. As shown in FIG. 2, in a long wavelength range of 635 nm˜700 nm, transmittance of red light rises as the viewing angle changes from 0° to 60°; in a short wavelength range of 450 nm˜490 nm, transmittance of blue light drops as the viewing angle changes from 0° to 60°; transmittance of light of middle wavelength keeps substantially the same. In other words, if the viewing angle increases constantly, transmittance of red light (λ≈700 nm) increases, whereas transmittance of blue light (λ≈440 nm) decreases, and therefore, color cast (bias towards red color) may occur at an oblique viewing angle, which affects picture quality.